JPH046657A - Rotary head device - Google Patents

Abstract

PURPOSE:To reduce fluctuation in pneumatic pressure and to realize forming of a stable and uniform air film with respect to a recording tape medium by cancelling pneumatic pressure fluctuation components of air delivered from two gaps between a couple of stator drums and a rotor. CONSTITUTION:Air is delivered from two minute gaps (a), (b) between a rotor 4 and a couple of stator drums 1, 2 through the rotation of the rotor 4 and a couple of stator drums 1, 2 through the rotation of the rotor 4. The delivered pressure of the air is delivered in a fluctuation state corresponding to the number of slots of spiral groups 11, 12, and since the phase of the spiral groups 11, 12 at the two gaps a, b is formed differently, the fluctuation of the delivered pressure of the air delivered from the two gaps (a), (b) is cancelled mutually to decrease the fluctuation. Thus, a uniform and stable air film is formed between the drum and the recording tape medium and the contact of a recording and reproducing head onto the tape is made stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotating head device used in a magnetic recording/reproducing device such as a video tape recorder (VTR).

[Summary of the invention]

In the present invention, a rotating body equipped with a recording/reproducing head is disposed between a pair of fixed drums, and surfaces of the fixed drums and the rotating body face each other across a small gap, that is, respective end surfaces of the fixed drums. Alternatively, by forming pump-out type spiral groups on both sides of the outer circumferential side of the rotating body that discharge the air from the internal space to the outside with different phases from each other, fluctuations in the air discharge pressure are reduced, and the drum The tape-shaped recording medium that is wound around and travels floats almost uniformly, that is, it becomes possible to form a uniform and stable air film, which reduces vibrations and stabilizes the head contact when the tape-shaped recording medium runs. It is designed to make it possible to achieve the following.

(Prior Art) Conventionally, as a rotating head device used in a VTR, a rotating tram is arranged between a pair of upper and lower fixed trams facing each other at a predetermined interval in the axial direction, with a small gap between them. A recording/reproducing head is attached to a cylindrical surface of a fixed drum, and is rotated around the same axis as the fixed drum while protruding outward from the cylindrical surface of the fixed drum. Recording on a magnetic tape that runs while being wound helically around the circumferential surface of the fixed drum. There is a so-called medium tram rotation type rotary head device that performs playback.

By the way, in this rotary head device, when the magnetic tape is wound around the outer circumference of the upper and lower fixed drums and is being run, the magnetic tape is highly deformable, so that - The contact state may not be in contact, and the contact state may vary greatly depending on the location, causing an unstable contact state with the recording/reproducing head rotated by the rotary drum, which may lead to unstable signal transmission.

Therefore, in order to solve this problem,
As disclosed in Japanese Patent No. 6361, a pump-out type spiral is provided on either the surface of the fixed cylinder or the surface of the rotating member facing the minute gap between the pair of upper and lower fixed cylinders and the rotating member to which the magnetic head is attached. A rotary head device in which a group is provided to discharge internal air to the outside so that the magnetic tape wound around a fixed cylinder floats above the circumferential surface of the fixed cylinder, thereby avoiding solid contact between the fixed cylinder and the magnetic tape. is proposed.

Problems to be Solved by the Invention] As described above, a spiral group for discharging air to either one of the opposing surfaces of a pair of upper and lower fixed cylinders and a rotating member that face each other across a small gap has been proposed in the past. In a rotary head device formed by a rotary head device, air flows through a pair of upper and lower fixed cylinders (21) and (22) as shown in FIG.
) and the rotating member (23), air is discharged from the upper and lower gaps a and b between the upper and lower fixed cylinders (23).
Discharge pressure fluctuations occur corresponding to the number of grooves in the spiral groups (11) and (12) formed on the end faces facing the gaps a and b of the spiral groups (11) and (22). 12) is formed symmetrically, the phase al+ of the air discharge pressure fluctuation from both gaps a and b
b+ becomes the same, and the air discharge pressure fluctuation increases (
a++b+), this causes the magnetic tape to vibrate with respect to the cylinder, which may result in unstable head contact.

The present invention has been made in view of the above problems, and reduces air pressure fluctuations by canceling out pressure fluctuation components of air discharged from two gaps between a pair of fixed drums and a rotating body, thereby reducing air pressure fluctuations. An object of the present invention is to provide a rotating head device that can realize uniform and stable air film formation between a recording medium and a recording medium.

[Means to solve the problem]

In order to achieve the above object, the rotary head device of the present invention includes a pair of fixed drums disposed on the same axis at a predetermined interval in the axial direction, and a rotary head device arranged between the fixed drums and on the outer periphery of the refixed drum. It consists of a rotating body that protrudes outward from the surface and has a recording/reproducing head that can rotate coaxially with the fixed drum, and a pair of fixed drums have a surface facing the outer surface of the rotating body with a small gap between them. Pump-out type spiral groups for discharging air from the internal space to the outside are formed at different phases on both sides of the rotating body or on each end face of the pair of fixed drums facing this minute gap.

C action] As described above, in the configuration of the present invention, air is discharged from two minute gaps between the rotary body and the pair of fixed drums by the rotation of the rotary body, and the discharge pressure of this air is spiral. The air is discharged in a fluctuating state depending on the number of grooves in the group, but since the spiral groups in the two gaps are formed with different phases from each other, the discharge pressure of the air discharged from the two gaps is The fluctuations in the equation cancel each other out to reduce this fluctuation.

This reduction in air discharge pressure fluctuations makes it possible to form a uniform and stable air film between the drum and the tape-shaped recording medium, thereby stabilizing the contact of the recording/reproducing head.

[Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a first embodiment will be explained with reference to FIGS. 1 to 4.

As shown in Fig. 1, the rotating head device of this example has an upper fixed drum (1) and a lower fixed drum (2) mounted on a fixed shaft (3).
A rotating body (4) is fixed in the axial direction with a predetermined gap, and is located in the gap between both drums (1) and (2).
is rotatably supported on a fixed shaft (3) by bearings (5) and (6), and the outer periphery and upper and lower surfaces (4a) (4b) of this rotating body (4)
There are minute gaps a and b between the lower outer surface (1a) of the upper fixed drum (1) and the upper outer surface (2a) of the lower fixed drum (2).
A recording/reproducing head, that is, a magnetic head (7 ) is fixed with its tip protruding outward from the cylindrical surface consisting of the re-fixing drums (1) and (2).

This rotating body (4) has a fixed shaft (3), a bearing (5), (
A magnet (8) is arranged on the outer periphery of the shaft cylinder part (4c) which is inserted through the magnet (6), and the lower fixed drum (4c) faces the magnet (8).
2) is rotationally driven by a direct drive motor configured by fixing a coil (9) to the inner periphery of the motor.

In this example, the outer circumferential lower surface part (Ia) of the upper fixed drum (1) and the outer circumferential upper surface part (2) of the lower fixed tram (2)
A pump-out type spiral group (11) and (12) are formed in a), and this spiral group (
11) and (12) are formed in the same direction as the rotating direction of the rotating body (4) and at positions shifted by 180 degrees from each other.

With this configuration, the rotating body (4) to which the magnetic head (7) is attached is rotated by the direct drive motor to the upper and lower outer peripheral surface portions (4a), (4b) of the upper and lower fixed drums (1), (2). and upper and lower fixed drums (1),
When rotating at high speed across the minute gaps a and b between the outer peripheral end surfaces (la) and (2a) of (2), the fixed drums (1) and (2) are formed by hydrodynamic action. The air in the internal space is discharged to the outside through the minute gaps a and b, but the air in the outer circumference (4a)
), (4b) facing fixed drums (1), (2
Pump-out type spiral groups (11) and (12) are formed on the outer peripheral end face portions (la) and (2a) of ), so that a large amount of air is discharged.

When this air is discharged, a discharge pressure fluctuation occurs that corresponds to the number of grooves in each spiral group (11) and (12), but the spiral groups (11) and (12) have a phase difference in position. Because of the difference of 18 degrees, the phases of the discharge pressure fluctuation components a and bl of the air generated from the gaps a and b are shifted by 180 degrees, as shown in FIG. This is canceled out, and fluctuations in the air discharge pressure are reduced.

This creates a more uniform and stable relationship between the upper and lower fixed drums (1), (2) and the tape-shaped recording medium, that is, the magnetic tape, which is wound and run across both drums (1), (2). As a result, tape vibration can be reduced, contact with the magnetic head (7) can be stabilized, and signal transmission can be performed more reliably.

In one embodiment described above, the upper and lower fixed drums (1
), (2) has spiral groups (11), (12
), but this spiral group (11)
, (12) is the upper and lower outer periphery of the rotating body (4) disposed between the upper and lower fixed drums (1) and (2) (4a) and (4).
b) may be formed.

That is, FIG. 5 shows another embodiment, in which the upper and lower fixed drums (
The outer peripheral lower surface part (1a) of 1) and the outer peripheral upper surface part (2a) of the lower fixed drum (2) are formed into a flat shape, and this lower surface part (1a)
) and the upper surface part (2a) with a small gap a and b in between. and this spiral group (11) and (1
2) are formed with their positions shifted by 180° in phase, as in the case of the above-mentioned embodiment.

Also in this example configured in this way, by forming the spiral groups (11) and (12) on the rotating body (4), when the rotating body (4) is rotated, the upper and lower fixed drums (IL ( Air is discharged from the gaps a and b between the spiral groups (11) and (12) with varying discharge pressure in accordance with the number of grooves in the spiral groups (11) and (12). Since the position is shifted by 18° from the air discharge pressure variation component a, the air discharge pressure variation component a and the air discharge pressure variation component a and the air discharge pressure variation component a and the air discharge pressure variation component a and the air discharge pressure variation component a and the air discharge pressure variation component a and the air discharge pressure variation component a, respectively, are offset by 18 degrees.

This action makes it possible to form a uniform and stable air film on the magnetic tape, reducing tape vibration and stabilizing the contact between the tape and the head.

Although the present invention has been described in detail above, the present invention is not limited to these embodiments, and can be modified in various ways without departing from the spirit of the present invention.

For example, by not only changing the position of the spiral group, but also changing the number of grooves, the groove pitch, the composition ratio of the groove part and the land part, etc., the fluctuation in the air discharge pressure can be further reduced.

Furthermore, a common groove can be further provided on the outer periphery of the surface having the spiral group.

[Effects of the Invention] As described above, according to the present invention, two parts of a pair of fixed drums and a rotary body to which a recording/reproducing head is attached are opposed to each other through two small gaps. A rotary head device that forms a pump-out type spiral group on a surface for discharging air from an internal space to the outside. The fluctuation in the discharge pressure corresponding to the number of air grooves discharged from the minute gaps in these locations is offset and reduced, creating a more uniform and stable relationship between the drum and the tape-shaped recording medium that is wound around it. By realizing air film formation, the vibration of the tape-shaped recording medium is reduced, the contact of the recording/reproducing head is stabilized, and signal transmission is performed reliably, making it possible to record and reproduce high-quality images, especially in video tape recorders. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a line sectional view of an example of a rotary head device according to the present invention, FIG. 2 is a bottom view of the upper fixed drum of the same device, and FIG.
The figure is a top view of the lower fixed drum of the same device, FIG. 4 is an explanatory diagram of the operation of one example of the present invention, FIG. 5 is an explanatory diagram of the operation of the other side of the present invention, and FIG. 6 is an explanatory diagram of the operation of the conventional example. be. In the figure, (1) and (2) are fixed drums, (4) is a rotating body, (7) is a magnetic head, (11) and (12) are spiral groups, and a and b are minute gaps. 1, 2 fixed tram 4 Okaro - 諫い本71叡へ, ト11.12 Snow＼'4UL7) L-7'α, b, @
Figure 1 Figure 3

Claims (1)

[Scope of Claims] A pair of fixed drums disposed coaxially at a predetermined interval in the axial direction, and a fixed drum disposed between the fixed drums and protruding outward from the outer peripheral surfaces of both fixed drums. and a rotating body having a recording/reproducing head that can rotate coaxially with the rotating body, and the pair of stationary drums have surfaces facing each other with a minute gap in between, and the pair of fixed drums have surfaces facing the outer surface of the rotating body with a minute gap between them. A rotary head device characterized in that pump-out type spiral groups for discharging air from the internal space to the outside are formed on both sides of the rotating body or on each end face of the pair of stationary drums with different phases from each other.